John gray



@einen 4 taten atrnt @frn JOHN I GRAY, OF LITCHAFIELD. ILLINOIS. Letters Patent No. 70,199, dated October 29. 1867.

IMPROVEMENT IN RAIGHET-DRILLS.

i wow- To ALL WHoM 1T MAY eoNeERN:

Be it known that I, JOHN GRAY, of Litchfield, in the county of Montgomery, and State of Illinois, have invented a new and 'useful Improvement in DrillStocks; and I do hereby declare that the following is a full and clear description thereof, reference being had to the accompanying drawings, and to the letters of reference marked thereon. p

This invention relates to u drill-stock, so constructed as to be self-acting in its feed-motion, and the feedniotion is so applied that there will bc a constant pressure brought to bear upon the drilling instrument, whether the resistance to .be Vovercome be much or little.

To enable those skilled in the art to malte and use my improved drill-stock, I will proceed to describe its construction andoperation.

Figure 1 of the drawings is a sectional elevation of the improved drill-stock.

Figure 2 is asimilar view of the feeding-screw.

Figure 3 is a horizontalsection of the top-end of the feeding-screw; and

Figure 4 is a. horizontal 4section ofthe bottom end of the same. i

It is to be distinctlyunderstood that the devices for producing a constantly regular and self-acting feed` motion-in the stock are the chief'features of this invention, and that these improvements are readily adaptable to a 1atchct-drill, drill-press, or any other form of'dr'illing machine, or to any drilling machine: now in use, but the following description will be particularly in reference to a ratchet-drill. The other applications can easily be made by any-good mechanic.

A is the drill-socket, and Al the lever by which it is turned. The ratchet attachment of these parts is very similar to those now in use, and need not, therefore, be minutely described. The fulcrum-rest B is also of the common form. The feeding-screw C is hollow for the reception of the spindle A2, which is a fixed portion of and co-axial with the drill-socket A. The top end of the spindle is conical in form,and iitted to a step in the sliding head Cl within the feeding-screw C. An elastic cushion or spring of India rubber or its equivalent, is interposed between the sliding head C1 and the xcd head C2 ef the screw, A dowel, e, projecting inwardly from the cylindrical feed-screw, is received in a groove in the side of the sliding head C, and prevents the latter from turning on its axis on the bearing of the spindle-head. The` lower end of the screw C is screwed4 into the cylindrical head D, and is xed imposition by means of the set-screws d d. These set-screws bear upon longitudinal notches e c, shown in section in gs. 1 and 2, and at different points in these notches, according as-the resistance of the spring C3 to the drill is intended to be greater or less. If a weak drill is used, the resistance l of the spring should be smallin order not to break the drill, and, therefore, the sleeve D should be set solas to bring its `lower end below that of the dowel a, in order that only a slight force may be required to push the dowcl within the sleeve. On the other hand, if a powerful drill is used, the resistance oi' the spring may be greater without damage, and the sleeve I) be set so as to bring its lower end above that of the dowel d. An inner flange, d', at the bottom end of the head D, forms anannular bearing for the spindle A2. A slot in one side of this annular bearing permits the dowel a, (which projects from theside of the spindle A2, as shown clearly' in iig. 4,) to pass vertically-through the said dange,'or to remain therein for thepurpose hereinafter more clearly explained. v y

The operation of the drill-stock, thus constructed, is as follows: When the feed-screw is turned down in its socket or'rest B, and pressure is thereby applied to the-spindle A2, as is customary, the action of such pressure upon the said spindle will cause it to force the elastic cushion up toward the fixed head C2, and thus relieve the pressure upon the drill-point, the said elastic cushion forcing the spindle Az down on the drill with a constant force when the drill is moved forward, thereby enabling it to cut a continuous chip of uniform thickness, without exerting undue pressure upon the drill at any time. The thickness of the flange al is such that if the pressure applied by the screw Cat any time becomes too great, the dowel a will slip above the said flange and thus stop the further motion of the screw until the cutting of the drill shall have relieved such pressure, and the said dowel a will slide down automatically into the groove in the dange, to again communicate. motion to it and to the feed-screw, when the spindle'is again turned in the proper 'direction- Having describedA my invention, what I claim isl l The combination of the feeding-screw C, with its head C2, the sliding head C1, the yielding cushion C3, the 'drill-spindle A, with its dowel a, and the cylindrical head D, with its llangc d', substantially as described.

In testimony of which invention I hereunto. set my handin presence of- JOHN GRAY.'

Witnesses:

M. RANDoLPn, Ouais. H. BoYLE. 

